Radiation Oncology/Toxicity/Brachial Plexus

Brachial Plexus RT Tolerance


 * Three distinct syndromes
 * Transient neuropathy
 * Classic, delayed, progressive fibrosis - unlikely to occur <60 Gy
 * Acute ischemic plexopathy


 * Dose constraints
 * RTOG 0236 (SBRT): 24/3
 * RTOG 0412 (RT+chemo): 60/30
 * RTOG 0435 (RT+chemo): 60/30
 * RTOG 0522 (RT+chemo): 60/30
 * RTOG 0615 (RT+chemo): 66/33
 * RTOG 0617 (RT+chemo): 66/33

Anatomy

 * For contouring, see also Radiation_Oncology/Anatomy


 * 2010 PMID 20631370 Full text -- "Brachial plexus contouring with CT and MR imaging in radiation therapy planning for head and neck cancer." (Truong MT, Radiographics. 2010 Jul-Aug;30(4):1095-103.)
 * Good images


 * RTOG; 2008 PMID 18448267 -- "Development and Validation of A Standardized Method for Contouring the Brachial Plexus: Preliminary Dosimetric Analysis Among Patients Treated with IMRT for Head-and-Neck Cancer." (Hall WH, Int J Radiat Oncol Biol Phys. 2008 Dec 1;72(5):1362-7.)
 * Delineation of brachial plexus established; images provided
 * Identify and contour C5, T1, and T2.
 * Identify and contour the subclavian and axillary neurovascular bundle
 * Identify and contour anterior and middle scalene muscles from C5 to insertion onto the first rib
 * To contour the brachial plexus OAR use a 5-mm diameter paint tool
 * Start at the neural foramina from C5 to T1; this should extend from the lateral aspect of the spinal canal to the small space between the anterior and middle scalene muscles
 * For CT slices, where no neural foramen is present, contour only the space between the anterior and middle scalene muscles
 * Continue to contour the space between the anterior and middle scalene muscles; eventually the middle scalene will end in the region of the subclavian neurovascular bundle
 * Contour the brachial plexus as the posterior aspect of the neurovascular bundle inferiorly and laterally to one to two CT slices below the clavicular head.
 * The first and second ribs serve as the medial limit of the OAR contour
 * Validation study; 2012 PMID 21536393 -- "Validating the RTOG-Endorsed Brachial Plexus Contouring Atlas: An Evaluation of Reproducibility Among Patients Treated by Intensity-Modulated Radiotherapy for Head-and-Neck Cancer." (Yi SK, Int J Radiat Oncol Biol Phys. 2012 Mar 1;82(3):1060-4.)
 * Conclusion: "The RTOG-endorsed brachial plexus atlas provides a consistent set of guidelines for contouring this OAR with essentially no learning curve. Adoption of these contouring guidelines in the clinical setting is encouraged."


 * Miami, 1996 PMID 8933882 -- "Radiation-induced brachial plexopathy: MR and clinical findings." (Bowen BC, AJNR Am J Neuroradiol. 1996 Nov-Dec;17(10):1932-6.)
 * Case report and literature review

Hyperbaric Oxygen

 * UK MRC -- hyperbaric oxygen vs control
 * Randomized, Phase II. 34 patients, radiation-induced brachial plexopathy. Median time to onset 3 years, median time to HBO 11 years. Arm 1) hyperbaric oxygen: 100% oxygen @ 2.4 ATA x 100 minutes x 30 dives vs Arm 2) Control: same number and pressure, but gas mix equivalent to 100% oxygen at surface
 * 2001 PMID 11230889 -- "Double-blind randomized phase II study of hyperbaric oxygen in patients with radiation-induced brachial plexopathy." (Pritchard J, Radiother Oncol. 2001 Mar;58(3):279-86.)
 * Outcome: No difference up to 12 months post-treatment, though some improvement. Two cases with chronic lymphedema reported major and persistent improvement
 * Conclusion: HBO doesn't slow or reverse RIBP